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An attractive, adaptable tree, white spruce (Picea glauca) and dwarf cultivers are an easy-care evergreen that adds warm color and distinctive fragrance to the yard. Dwarf white spruce makes a good container plant. The trees grow well in full sun to partial shade and like moist soil with good drainage. White spruce grows best in U.S. Department of Agriculture plant hardiness zones 2 through 7, but also does well in warmer areas. The tree tolerates salty coastal areas. White spruce trees grow about 65 feet tall. Several diseases can cause problems with all white spruce varieties.

Rots and Decays

Caused by several Phytophthora species, crown, collar, foot or root rot causes distorted, wilting or stunted foliage. Cankers may form on the tree, or stains appear on the bark as black or reddish sap oozes from the infection site. The tree may suffer dieback. In severe cases, the whole tree may die, though the death may take years. Cut away the bark around the stains or cankers, and look for water-soaked wood that is darker than the tissue around it. This indicates phytophthora rot. Keep the tree properly irrigated, and improve drainage if necessary to avoid standing water around the roots of the spruce. If the spruce has contracted crown rot, try removing soil around the base of the tree to expose the main roots, giving them a chance to dry out. Sanitize gardening tools and prune the canopy, if practical, to improve air circulation so the needles and branches dry more thoroughly after rainfall.

Crown Gall

Agrobacterium tumefaciens is a bacterial pathogen that causes galls to form on the crown, or top portion of the roots. Galls may also appear on limbs and trunks. When young white spruce trees are infected, growth may be stunted and stressed. Galls encircling, or girdling, young spruce trunks usually kill the trees. Galls may be small, smooth and warty, or large and woody. Avoid planting new white spruce trees in areas of the yard where crown gall has been a problem before. Cut away existing galls, taking a margin of healthy tissue along with it to be sure the infection is completely excised. Do this during dry periods, and allow the wound to dry and heal on its own.

Needle Cast Fungi

Needle cast infections are caused by several different fungi. The disease causes chlorosis, or fading of needle color, and may cause dark lesions, spots or streaks on the stems and needles. Cankers may form on the wood, with brown streaks nearby. Although needle cast infections normally won't kill a healthy white spruce, they can cause the spruce to drop, or cast, its needles and kill branches. By the time the spruce's needles become discolored and begin to fall from the tree, the infection is already a year or more old. Lower branches display symptoms first. Get rid of vegetation and weeds near the white spruce tree, and prune the tree's lower branches. When the weather is dry, prune infected needles and branches, and destroy them away from the yard. Disinfect pruning tools between cuts, and thin the tree's canopy, if practical, to improve air circulation. Fungicides containing copper may be used to treat the infection. Treatment takes at least two years. Follow label directions for proper application rates and timing.

Rust

Rusts are another type of fungal infection that may attack white spruce trees. The disease causes needles to yellow and drop from the tree. You may find reddish to orange spore pustules on the upper or lower surface of the needles. Some types of rust fungi may cause galls and cankers. Healthy trees can recover; but if left untreated, some rust infections can kill white spruce. Gather and destroy all plant debris from around the tree, and prune out as much of the infected branches as possible as soon as they are discovered. Spray the tree with a fungicide in spring as a preventive. Follow label directions for proper timing and application rates.

Wood Decay Fungi

Wood decay is an invisible destroyer, growing and spreading deep in the center of the white spruce tree and killing from within. Older trees are more susceptible than young trees. Wood decay, caused by a variety of fungal infections, weakens the heart of the tree and destroys conductive tissue. In some cases, the tree develops a cavity that indicates wood decay is present, or the fungi produce fruiting bodies on the lower outside portion of the trunk. These may look like mushrooms or like fleshy "shelves" that protrude from the trunk. Each fungi produces a different type of fruiting body that can help identify it. Keep the tree healthy, and avoid wounding the tree with lawn mower strikes or improper pruning. Watch for boring insects that can tunnel into the wood, giving fungal spores a doorway into the tree. Prune dead or diseased limbs. Monitor the tree as much as possible, since trees suffering from wood decay can topple or drop large limbs without warning and pose a significant hazard.

About the Author

Audrey Lynn has been a journalist and writer since 1974. She edited a weekly home-and-garden tabloid for her hometown newspaper and has regularly contributed to weekly and daily newspapers, as well as "Law and Order" magazine. A Hambidge Fellow, Lynn studied English at Columbus State University.